

A162469


Number of reduced words of length n in the Weyl group D_49.


0



1, 49, 1224, 20776, 269499, 2848811, 25555215, 200037215, 1394396185, 8790665065, 50733161116, 270672378844, 1345758869770, 6277354061930, 27627446293371, 115285643098059, 458048619713020, 1739199358769180
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OFFSET

0,2


COMMENTS

Computed with MAGMA using commands similar to those used to compute A161409.


REFERENCES

N. Bourbaki, Groupes et alg. de Lie, Chap. 4, 5, 6. (The group is defined in Planche IV.)
J. E. Humphreys, Reflection Groups and Coxeter Groups, Cambridge, 1990. See under Poincare polynomial.


LINKS

Table of n, a(n) for n=0..17.


FORMULA

G.f. for D_m is the polynomial f(n) * Product( f(2i), i=1..n1 )/ f(1)^n, where f(k) = 1x^k. Only finitely many terms are nonzero. This is a row of the triangle in A162206.


CROSSREFS

Sequence in context: A163005 A161694 A162204 * A011001 A115999 A228258
Adjacent sequences: A162466 A162467 A162468 * A162470 A162471 A162472


KEYWORD

nonn


AUTHOR

John Cannon and N. J. A. Sloane, Dec 01 2009


STATUS

approved



